Btrfs: Full back reference support

This patch makes the back reference system to explicit record the
location of parent node for all types of extents. The location of
parent node is placed into the offset field of backref key. Every
time a tree block is balanced, the back references for the affected
lower level extents are updated.

Signed-off-by: Chris Mason <chris.mason@oracle.com>

1 files changed, 58 insertions, 50 deletions

diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index 56de3fb2d8d5..88bbfd959f18 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -89,9 +89,9 @@ int btrfs_add_log_tree(struct btrfs_trans_handle *trans,
         int ret;
         u64 objectid = root->root_key.objectid;
 
-        leaf = btrfs_alloc_free_block(trans, root, root->leafsize,
+        leaf = btrfs_alloc_free_block(trans, root, root->leafsize, 0,
                                       BTRFS_TREE_LOG_OBJECTID,
-                                      0, 0, 0, 0, 0);
+                                      trans->transid, 0, 0, 0);
         if (IS_ERR(leaf)) {
                 ret = PTR_ERR(leaf);
                 return ret;
@@ -433,6 +433,49 @@ insert:
                                                    trans->transid);
                 }
         }
+
+        if (overwrite_root &&
+            key->type == BTRFS_EXTENT_DATA_KEY) {
+                int extent_type;
+                struct btrfs_file_extent_item *fi;
+
+                fi = (struct btrfs_file_extent_item *)dst_ptr;
+                extent_type = btrfs_file_extent_type(path->nodes[0], fi);
+                if (extent_type == BTRFS_FILE_EXTENT_REG) {
+                        struct btrfs_key ins;
+                        ins.objectid = btrfs_file_extent_disk_bytenr(
+                                                        path->nodes[0], fi);
+                        ins.offset = btrfs_file_extent_disk_num_bytes(
+                                                        path->nodes[0], fi);
+                        ins.type = BTRFS_EXTENT_ITEM_KEY;
+
+                        /*
+                         * is this extent already allocated in the extent
+                         * allocation tree?  If so, just add a reference
+                         */
+                        ret = btrfs_lookup_extent(root, ins.objectid,
+                                                  ins.offset);
+                        if (ret == 0) {
+                                ret = btrfs_inc_extent_ref(trans, root,
+                                                ins.objectid, ins.offset,
+                                                path->nodes[0]->start,
+                                                root->root_key.objectid,
+                                                trans->transid,
+                                                key->objectid, key->offset);
+                        } else {
+                                /*
+                                 * insert the extent pointer in the extent
+                                 * allocation tree
+                                 */
+                                ret = btrfs_alloc_logged_extent(trans, root,
+                                                path->nodes[0]->start,
+                                                root->root_key.objectid,
+                                                trans->transid, key->objectid,
+                                                key->offset, &ins);
+                                BUG_ON(ret);
+                        }
+                }
+        }
 no_copy:
         btrfs_mark_buffer_dirty(path->nodes[0]);
         btrfs_release_path(root, path);
@@ -551,45 +594,10 @@ static noinline int replay_one_extent(struct btrfs_trans_handle *trans,
                          start, extent_end, start, &alloc_hint);
         BUG_ON(ret);
 
+        /* insert the extent */
+        ret = overwrite_item(trans, root, path, eb, slot, key);
         BUG_ON(ret);
-        if (found_type == BTRFS_FILE_EXTENT_REG) {
-                struct btrfs_key ins;
-
-                ins.objectid = btrfs_file_extent_disk_bytenr(eb, item);
-                ins.offset = btrfs_file_extent_disk_num_bytes(eb, item);
-                ins.type = BTRFS_EXTENT_ITEM_KEY;
-
-                /* insert the extent pointer in the file */
-                ret = overwrite_item(trans, root, path, eb, slot, key);
-                BUG_ON(ret);
 
-                /*
-                 * is this extent already allocated in the extent
-                 * allocation tree?  If so, just add a reference
-                 */
-                ret = btrfs_lookup_extent(root, path, ins.objectid, ins.offset);
-                btrfs_release_path(root, path);
-                if (ret == 0) {
-                        ret = btrfs_inc_extent_ref(trans, root,
-                                   ins.objectid, ins.offset,
-                                   root->root_key.objectid,
-                                   trans->transid, key->objectid, start);
-                } else {
-                        /*
-                         * insert the extent pointer in the extent
-                         * allocation tree
-                         */
-                        ret = btrfs_alloc_logged_extent(trans, root,
-                                                root->root_key.objectid,
-                                                trans->transid, key->objectid,
-                                                start, &ins);
-                        BUG_ON(ret);
-                }
-        } else if (found_type == BTRFS_FILE_EXTENT_INLINE) {
-                /* inline extents are easy, we just overwrite them */
-                ret = overwrite_item(trans, root, path, eb, slot, key);
-                BUG_ON(ret);
-        }
         /* btrfs_drop_extents changes i_blocks, update it here */
         inode->i_blocks += (extent_end - start) >> 9;
         btrfs_update_inode(trans, root, inode);
@@ -1806,16 +1814,14 @@ static int noinline walk_up_log_tree(struct btrfs_trans_handle *trans,
                         WARN_ON(*level == 0);
                         return 0;
                 } else {
-                        if (path->nodes[*level] == root->node) {
-                                root_owner = root->root_key.objectid;
-                                root_gen =
-                                   btrfs_header_generation(path->nodes[*level]);
-                        } else {
-                                struct extent_buffer *node;
-                                node = path->nodes[*level + 1];
-                                root_owner = btrfs_header_owner(node);
-                                root_gen = btrfs_header_generation(node);
-                        }
+                        struct extent_buffer *parent;
+                        if (path->nodes[*level] == root->node)
+                                parent = path->nodes[*level];
+                        else
+                                parent = path->nodes[*level + 1];
+
+                        root_owner = btrfs_header_owner(parent);
+                        root_gen = btrfs_header_generation(parent);
                         wc->process_func(root, path->nodes[*level], wc,
                                  btrfs_header_generation(path->nodes[*level]));
                         if (wc->free) {
@@ -2525,8 +2531,10 @@ static noinline int copy_items(struct btrfs_trans_handle *trans,
                                 if (ds != 0) {
                                         ret = btrfs_inc_extent_ref(trans, log,
                                                    ds, dl,
+                                                   dst_path->nodes[0]->start,
                                                    BTRFS_TREE_LOG_OBJECTID,
-                                                   0, ins_keys[i].objectid,
+                                                   trans->transid,
+                                                   ins_keys[i].objectid,
                                                    ins_keys[i].offset);
                                         BUG_ON(ret);
                                 }